class A:

    def foo(self):
        print('foo() in A')


class B(A):

    def foo(self):
        print('foo() in B')


class C(A):

    def foo(self):
        print('foo() in C')


class D(C, B):
    pass


def main():
    print(D.__mro__)
    obj = D()
    obj.foo()


if __name__ == '__main__':
    main()
